Loud speaker construction



Nov. 8, 1966 c. L. FENDER 3,284,581

LOUD SPEAKER CONSTRUCTION Filed June 5, 1963 2 Sheets-$heet '1.

CZ/QIQEA/CE L. 1 271405? INVENTOR.

W f /z Nov. 8, 1966 c. L. FENDER 3,284,581

LOUD SPEAKER CONSTRUCTION Filed June 5, 1963 2 Sheets-Sheet 2,

visas S United States Patent Office 3,284,581 LOUD SPEAKER CONSTRUCTIONClarence L. Fender, Fullerton, Calif., assignor, by mesne assignments,to Columbia Broadcasting System, Inc., New York, N.Y., a corporation ofNew York Filed June 3, 1963, Ser. No. 284,905 6 Claims. (Cl. 179-1155)This invention pertains to loud speakers and, more particularly, to anarrangement for protecting the leads of a speaker coil.

The usual loud speaker includes a voic coil of relatively fine wirewound upon a cylinder .located at the apex of the speaker cone. Theleads from the coil are brought out along the inner surface of thespeaker cone, where they are held with a suitable cement, and passthrough the speaker wall for attachment into the amplifier circuit. Thistype of construction, while accepted as conventional design and nearlyuniversally used, has led to a troublesome problem from breakage of thecoil leads. The vibration of the speaker diaphragm frequently will causea fatigue failure of the fine coil fires at the juncture between thecoil and the speaker cone. Consequently, after only a short period ofservice many loud speakers will malfunction from the crystallization andresultant breakage of the coil leads.

The present invention provides a simple, .low cost olution to thisdifliculty, protecting the lead wires so they will not become broken butwill remain intact throughout the life of the speaker. This isaccomplished by wrapping an external layer of paper over the leads atthe forward edge of the coil bobbin, assuring that the leads are notconnected directly to the cone surface at its inner periphery.Consequently, the lead wires are not attached at the portion of thespeaker cone that is receiving the maximum vibration, and failure fromdiaphragm vibration is eliminated.

An object of this invention is to provide a loud speaker of durable,long-life construction.

Another object of this invention is to provide a simple, low costarrangement for precluding breakage of lead wires of the coil of a loudspeaker. A further object of this invention is to provide a means forprotecting the lead wires of a speaker coil, assuring that they are notattached to the portion of the speaker cone that is vibrated the maximumamount.

These and other objects will become apparent from the following detaileddescription taken in connection with the accompanying drawings in which:

FIGURE 1 is a fragmentary plan view of aloud speaker coil illustratingthe manner in which the lead wires extend therefrom,

FIGURE 2 is an axial sectional view of a complete loud speaker unitmanufactured in accordance with this invention,

FIGURE 3 is an enlarged fragmentary sectional view of the centralportion of the unit of FIGURE 2,

FIGURE 4 is a further enlarged fragmentary sectional view illustratingthe coil lead wire and its attachment to the speaker cone, and

FIGURE 5 is a view similar to FIGURE 4, showing the invention asassociated with a slightly modified speaker construction.

With reference to the drawings, there may be seen in FIGURE 1 a portionof a typical loud speaker voice coil construction separated from theremainder of the speaker assembly. This coil unit is defined by a lengthof wire helically wrapped in two layers, and doubled back on itself atone end portion of a bobbin 11. 'Dhe latter member is a thin cylindricaltube, and may be made of relatively light paper having suflicientrigidity to hold its 3,284,581 Patented Nov. 8, 1966 shape. With thecoil 10 being formed from a continuous length of wire, the two leads 12and 13 may be brought away from one end of the coil across the surfaceof the bobbin.

The voice coil may be associated with a typical loud speaker 15, asillustrated in FIGURE 2, being positioned at the apex of the speakercone 16. The latter member is mounted within a metal housing 17 thatsupports the speaker components. The coil is free to move axially but isprecluded from appreciable radial movement by a spider 18. This i acorrugated diaphrgam, the outer edge of which is connected to thehousing 17. The inner edge of the spider .18 meets the inner peripheralflange 19 of the speaker cone 16, being bonded with that element to theexterior surface of the coil bobbin assembly.

On the rear side of the frame is a permanent magnet 20, in this instancea ceramic magnet of annular construction, which is mounted betweenplates 21 and 22. The plate 21 i of magnetic material and carries a polepiece 24 that extends into the bobbin 11 inwardly of thehelically-wrapped coil 10.

According to the provisions of this invention, as the voice coil unit ismanufactured the leads 12 and 13 are positioned on the surface of thebobbin 11 to extend forwardly over the radial edge 25 of the bobbin.Then there is placed around the exterior of the bobbin, covering theleads 12 and 13, an additional layer of paper 26. This element mayextend from the end of the coil 10 to the outer edge 25 of the bobbin11. This means that the leads 12 and 13 must be adjacent the entirelength of the bobbin 11. Consequently, the leads 12 and 13 extend intothe interior of the speaker cone to the edge 25 of the bobbin, which isaxially forward of the inner edge 19 of the conical speaker diaphragm.From this point, the leads are inclined outwardly to the inner surfaceof the speaker cone, being bonded to that element by a suitable adhesivesubstance 28. After a short distance on the face of the cone, the leadspass through the wall of the element 16 to the rear side, and from thereto the circuitry of the unit with which the loud speaker is associated.

The relatively simple provision of the outer layer of paper 26 protectsthe leads 12 and 13 so that they will not be damaged by the vibration ofthe speaker cone 16. This results because the outer sleeve 26 is spacedfor- 'wardly of the inner edge 19 of the speaker cone. Consequently, themember 26 acts as a barrier membrane, and the leads necessarily arebrought out to .a point of attachment beyond the area immediatelyadjacent the edge 19. It is the portion of the cone next to the innerperipheral edge that receives the maximum vibration as the loud speakeris used. In conventional construction, the leads are connected to thespeaker cone at its inner edge, extending outwardly from that edge alongthe surface of the cone. Therefore, by the usual construction the leadsare bonded to the surface of the cone directly adjacent the inner edge19. By being secured in this zone of extreme vibration, the leads of thevoice coil of a conventional loud speaker quite easily can become brokenfrom the oscillation of the speaker cone. However, by including asuitable barrier element, which necessarily results in the attachment ofthe leads outwardly of the inner peripheral edge of the cone, thisdifficulty is avoided. The reliability of the construction and the lifeof the lead wires are improved greatly. At the same time, thisarrangement adds practically no cost to the manufacturing process, beingadapted to mass production techniques and requiring very little time toaccomplish. Typically, the element 26 merely is wrapped around the endof the bobbin to form a sleeve which is secured in place by adhesive.The attachment of the spider and inner edge of the cone will be made tothis outer layer of the coil unit.

While it is preferred to construct the loud speaker cone as illustratedin FIGURES 2, 3 and 4, in which the inner portion of the element is of atrue conical shape, such a configuration is difiicult to achieve. Asapractical matter, a speaker cone normally will have a shape such asshown in FIGURE 5. Here the cone 30 includes a short sub stantiallyradially extending portion 31 adjacent the flange 32 at its innerperiphery. The radial portion 31 is subjected to even more pronouncedmovement than the inner edge of a speaker element that is of more exactconical configuration. Hence, the problem of lead wire fatigue failureor breakage is aggravated as a consequence of the structure almostinvariably given to a speaker cone. Nevertheless, as seen in FIGURE 5,the provision of this invention still assures that the lead wires arebonded to the surface of the cone outwardly of the inner edge portion,including a considerable space from the radial portion 31 of the cone.Again, therefore, the lead wires join the cone at a location away fromthe portion of greatest vibration, and the leads are protected frombreakage.

The foregoing detailed description is to be clearly understood as givenby way of illustration and example only, the spirit and scope of thisinvention being limited solely by the appended claims.

I claim:

1. In combination with a loud speaker having a speaker cone having anaperture at the apex thereof, a voice coil arrangement comprising acylindrical bobbin extending through said aperture to an end portionadjacent and inwardly of said aperture, a coil of wire on the oppositeend portion of said bobbin,

said coil having electrical leads extending therefrom through saidaperture,

said leads extending to the surface of said cone adjacent but radiallyoutward of said aperture,

a membrane extending over said leads adjacent said first-mentioned endof said bobbin for spacing said leads from said speaker cone at saidaperture,

and adhesive means securing said leads to said surface.

2. A device as recited in claim 1 in which said membrane comprises alayer of paper overlying said leads and bobbin.

3. In combination with a loud speaker having a speaker cone having anaperture through the apex thereof, a voice coil arrangement for saidloud speaker comprising a paper tube,

one end of said tube extending axially through said aperture to an edgeinwardly of said speaker cone and adjacent said aperture, ahelically-wound coil of wire on the opposite end of said tube,

said wire having a duality of leads extending axially from the end ofsaid helicallywound coil adjacent said one end of said tube,

said leads extending along the surface of said tube through saidaperture,

a paper strip adhesively secured over said tube and said leads,

said strip extending substantially from said end of said coil to thefirst-mentioned end of said tube, said leads thereby being constrainedto said first-mentioned end of said tube and extending outwardlythereof,

and adhesive means securing said leads to the surface of said speakercone adjacent but radially outwardly of said aperture.

4. In combination with a loud speaker having a conical diaphragm havingan annular apical edge, a voice coil comprising a tubular bobbin,

a helically-wrapped wire on one end of said bobbin, the opposite end ofsaid bobbin extending into said conical diaphragm beyond said annularapical edge,

a barrier member secured to said opposite end of said bobbin andextending into said conical diaphragm beyond said apical edge,

said conical diaphragm being ecured to said barrier member at saidapical edge, said helically-wrapped wire having a duality of leads, saidleads extending over said bobbin and beneath said barrier to saidopposite end, and from said opposite end to the inner face of saidconical diaphragm at a location radially outward of said apical edge,

and means securing said leads to said conical diaphragm at saidlocation.

5. A device as recited in claim 4 in which said barrier is a papersleeve on said bobbin, and said means for securing said leads to saidconical diaphragm includes an adhesive.

6. A voice coil assembly for a loud speaker comprising a cylindricalbobbin adapted to fit within a speaker cone at the apex thereof,

a helically-wound length of wire carried by said bobbin at one endthereof,

said helicallyawound length of wire having a duality of leads extendingtherefrom along the surface of said bobbin to and beyond the oppositeend of said bobbin,

and a barrier member secured over the surface of said bobbin and saidleads for precluding separation of said leads from said bobbin,

said barrier member being a paper sleeve bonded to the circumferentialsurface of said bobbin.

References Cited by the Examiner FOREIGN PATENTS 415,444 8/1934 GreatBritain.

KATHLEEN H. CLAFFY, Primary Examiner.

ROBERT H. ROSE, Examiner.

F, N, CARTEN, Assistant Examiner.

1. IN COMBINATION WITH A LOUD SPEAKER HAVING A SPEAKER CONE HAVING ANAPERTURE AT THE APEX THEREOF, A VOICE COIL ARRANGEMENT COMPRISING ACYLINDRICAL BOBBIN EXTENDING THROUGH SAID APERTURE TO AN END PORTIONADJACENT AND INWARDLY OF SAID APERTURE, A COIL OF WIRE ON THE OPPOSITEEND PORTION OF SAID BOBBIN, SAID COIL HAVING ELECTRICAL LEADS EXTENDINGTHEREFROM THROUGH SAID APERTURE, SAID LEADS EXTENDING TO THE SURFACE OFSAID CONE ADJACENT BUT RADIALLY OUTWARD OF SAID APERTURE, A MEMBRANEEXTENDING OVER SAID LEADS ADJACENT SAID FIRST-MENTIONED END OF SAIDBOBBIN FOR SPACING SAID LEADS FROM SAID SPEAKER CONE AT SAID APERTURE,AND ADHESIVE MEANS SECURING SAID LEADS TO SAID SURFACE.